Embodiments of the present invention relate generally to wireless power transfer systems and more particularly relate to over voltage protection for a wireless power transfer system.
In one or more industries, an electric vehicle or a hybrid vehicle includes one or more batteries that supply electrical power to drive the vehicle. In one example, the batteries supply energy to an electric motor to drive a shaft in the vehicle, which in turn drives the vehicle. The batteries are used for supplying the power and hence may be drained and need to be charged from an external power source.
In general, power transfer systems are widely used to transfer power from a power source to one or more electric loads, such as for example, the batteries in the vehicle. Typically, the power transfer systems may be contact based power transfer systems or contactless power transfer systems. In the contact based power transfer systems, components, such as plug, socket connectors, and wires are physically coupled to the batteries for charging the batteries. However, due to environmental impact, such connectors and wires may be damaged or corroded. Also, high currents and voltages are used for charging the batteries. Hence, establishing a physical connection between the power source and the batteries in the vehicle may involve cumbersome safety measures. Also, this power transfer system may become bulkier and heavier compared to the contactless power transfer system.
In the contactless power transfer systems, power converters are used to convert an input power to a transferrable power, which is further transmitted to the electric load, such as the batteries in the vehicle. The power converter includes switches which are operated at a particular switching frequency to convert the input power to the transferrable power. Typically, depending upon the load, the switching frequency of the power converter is changed to regulate or control an output voltage of the power transfer system. However, if the electric load is disconnected or varied, the output voltage of the power transfer system may attain a very high value in a very short time period. Such a sudden increase in the output voltage may lead to failure of operation and may also damage one or more components in the power transfer system.
Therefore, there is a need for an improved system and method for protecting the power transfer system.